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CHM151 Name: ______KEY______

Sample Exam 3 – Chapters 8, 9, 10 Show ALL work for FULL credit!!

1. Which of the following substances crystallizes as a molecular solid? a. NaCl b. CO2 c. Au d. K2CO3 e. CaO

2. Circle ALL of the IMF’s present for each of the following substances:

A. B. C. D. LDF DDF HBF LDF DDF HBF LDF DDF HBF LDF DDF HBF

3. Which of the following properties indicates the presence of weak intermolecular forces in a liquid? a. a high b. a high c. a high d. a high

4. Which of the following should have the highest boiling point at a given temperature? a. , CH4 b. tetrafluoride, CF4 c. , CCl4 d. , CBr4 e. , CI4

5. Refer to the phase diagram provided to answer the following questions: a. What is the normal boiling point for this substance? 105ºC b. What is the physical state for this substance at 1.5 atm and 150°C? liquid c. Circle the vaporization curve on the phase diagram below.

6. Calculate the heat of reaction, ΔH°, for the reaction:

3 NO2 (g) + H2O (l) → 2 HNO3 (aq) + NO (g)

Substance: NO2(g) H2O (l) HNO3 (aq) NO (g)

ΔH°f (kJ/mol) 33.2 -285.5 -119.0 91.3

ΔHºrxn = 39.2 kJ

7. Determine the amount of heat released when 26.9 mL methanol, CH3OH (density = 0.792 g/mL), reacts according to the following combustion equation: 2 CH3OH (l) + 3 O2 (g) → 2 CO2 (g) + 4 H2O (l) ΔH°rxn = -1452.8 kJ/mol

ΔHºrxn = -483 kJ

8. Use the given average bond dissociation energies to estimate ΔH for the reaction of methane, CH4 (g), with :

____ CH4 (g) + __2__ F2 (g) → ____ CF4 (g) + __2__ H2 (g) Bond EBDE, kJ/mol H-H 436 C-F 450 ΔHºrxn = -716 kJ C-H 410 F-F 158

9. List the following ionic compounds in order of increasing lattice energy: Li3P, Sr3P2, Mg3P2, AlP,

Lowest LE _Li3P__ > __Sr3P2_ > __Mg3P2__ > __AlP__ > Highest LE

10. Which of the following equations represents a heat of formation equation?

a. C (s) + O2 (g) → CO2 (g)

b. 2 Au (s) + 3 Cl2 (g) → 2 AuCl3 (s) c. Cl (g) + Na (s) → NaCl (s)

d. CaO (s) + CO2 (g) → CaCO3 (s)

11. What type of bond typically has the highest bond enthalpy value? a. single b. double c. triple d. all three have the same value for bond enthalpy

12. Which of the following has a standard enthalpy of a formation value (ΔHf°) of zero?

H2O (l) O3 (g) Br2 (l) O (g) CO2 (s)

13. Which ionic compound is the most stable? a. CaO b. K2O c. SrO d. Rb2O

14. When bonds are broken in a chemical reaction, this process is considered ______. a. exothermic b. endothermic

15. Find ΔH for BaCO3 (s) → BaO (s) + CO2 (g)

given 2 Ba (s) + O2 (g) → 2 BaO (s) ΔH = -1107.0 kJ

Ba (s) + CO2 (g) + ½ O2 (g) → BaCO3 (g) ΔH = -822.5 kJ ΔH = 269.0 kJ

16. Which one of the following is not used to describe the condition of a gas? a. number of moles b. polarity c. temperature d. volume

17. Boyle’s Law states that pressure is a. directly related to volume b. inversely related to volume c. directly related to temperature d. inversely related to temperature

18. A basketball is inflated to a pressure of 1.50 atm in a 20.0°C garage. What is the pressure of the basketball outside where the temperature is -5.0°C? (Assume V and n are constant) a. 1.37 atm b. 1.42 atm c. 1.58 atm d. 1.64 atm

19. Which of the following would have a density of 1.21 g/L at 280.15°C and 0.993 atm?

a. Ar b. N2 c. Ne d. O2

20. What is the total pressure in a 3.00 L container containing 0.310 moles of N2 and 0.250 mole of O2 at 303 K? a. 4.64 atm b. 4.55x10-4 atm c. 0.215 atm d. 1.00 atm

21. Which of the following gases has the highest average speed at 400K?

a. CO2 b. N2O4 c. F2 d. SF6

22. A process by which gas escape through a tiny hole in a membrane into a vacuum without collisions is called a. Boyle's law. b. diffusion. c. sublimation. d. effusion.

23. Of the following statements, which describes properties of an ideal gas? a. Gases are highly compressible. b. There are relatively large distances between gas molecules in a container. c. Gases form homogeneous mixtures and do not react with other gas molecules. d. All of the above.

24. The specific capacity heat of copper is 0.385 J/(g°C). If 34.2 g of copper, initially at 25°C, absorbs 4.689 kJ, what will be the final temperature of the copper? a. 356 °C b. 381 °C c. 25.4 °C d. 27.8 °C

25. What mass of gas occupies a 4.50L container at 55.6ºC and 887 torr? PV=nRT solve for n = 0.19468 moles Cl2 Now use to get grams = 13.8 gCl2

26. What volume of hydrogen gas is produced when 6.75 g of aluminum is placed in excess 4.0 M HCl at 33.8 ºC and 956.4 torr according to the equation 2Al(s) + 6HCl(aq) → 3H2(g) + 2AlCl3(aq)? 6.75 g Al( 1 mol Al )( 3 mol H2) = 0.375 mol H2 (26.98 g Al)(2 mol Al ) -1 -1 PV=nRT V = nRT = (0.375 mol H2)(0.08206 L atm mol K )(306.95K)= 7.51 L P (1.2584 atm)

27. How much heat is absorbed when 30.00 g of C (s) reacts in the presence of excess SO2 (g) to produce CS2 (l) and CO (g) according to the following chemical equation? 5 C (s) + 2 SO2 (g) → CS2 (l) + 4 CO (g) ΔH° = +239.9 kJ 30.00 g C ( 1 mol C )(239.9 kJ )= 119.9 kJ (12.011 g C)( 5 mol C)

28. Which of the following would exhibit -dipole forces as the strongest force between molecules? a. HCN b. CCl4 c. CH3OH d. C6H6

29. Which of the following will have the lowest boiling point? a. CH3CH2CH2NH2 b. CH3CH2CH2SH c. CH3CH2CH2OH

30. Solid , CO2 (s), is what type of crystalline solid? a. molecular b. ionic c. metallic

31. What type of , IMF, would be present between molecules in a sample of Br2 (l)? a. LDF b. DDF c. HBF d. -Dipole Forces

32. What is the strongest IMF present between like molecules in a sample of H2S (l)? a. LDF b. DDF c. HBF d. Ion-Dipole Forces

33. What type of bond is present between in a sample of CO2? a. nonpolar covalent b. polar covalent c. LDF d. James

34. Hexane, C6H12, is an organic found in gasoline. Circle the property of liquids that would have a relatively high value for hexane. a. vapor pressure b. surface tension c. boiling point d. viscosity

35. Which molecule will have the highest boiling point? a. I2 b. Br2 c. Cl2 d. F2

36. Select the correct molecule with the lowest surface tension. a. CH3CH2CH2Cl b. CH3CH2CH2NH2 c. CH3CH2CH2CH3

37. Select the molecule that has HBF as it’s strongest IMF between like molecules. a. CH3CH2CH2SH b. CH3CH2CH2OH c. CH3CH2OCH2CH3

38. What is the strongest force present between like particles in a sample of liquid mercury, Hg (l)? a. London Dispersion Forces b. Ionic Bonds c. Covalent Bonds d. Metallic Bonds